The effectiveness of incident management on network reliability – Stage 2

This research investigated how ITS (Intelligent Transport Systems) measures), such as adaptive signal control (e.g. SCATS®) and Variable Message Signing (VMS), can be used to improve the transport network efficiency during traffic incidents. Following a literature review, a motorway and arterial road traffic network was modelled to determine the most appropriate traffic management strategies (in terms of overall network reliability) to apply when such incidents are detected. For a motorway blockage scenario, the chosen mitigation (implementing VMS and allowing use of the motorway hard-shoulder) was estimated to produce a 20% reduction in average trip times, although on some selected diversion routes the estimated effect was less than 7%. The reduction in the standard deviation of trip times was much larger (~80%). For an arterial road lane closure, the chosen mitigation (revising the SCATS® management plan) was estimated to produce quite small improvements in average travel times (less than 2%). The estimated effect on various diversion routes varied considerably up and down. For a large complex network, it may be necessary to have a large number of incident management plans, to cover the range of incident scenarios that might occur. A ‘template’ process is proposed for identifying the most significant risks to a network, comparing the treatment options, and developing suitable contingency management plans.